1. Field
The present disclosure is directed to a method and apparatus for low latency transmissions. More particularly, the present disclosure is directed to wireless transmissions, signaling, and frame structures for devices configured for low latency data packets while maintaining backward compatibility with devices configured for normal latency data packets.
2. Introduction
Presently, users use wireless communication devices, otherwise known as User Equipment (UE), such as smartphones, cell phones, tablet computers, selective call receivers, and other wireless communication devices, on Long Term Evolution (LTE) networks, Wireless Local Area Networks (WLANs), and other wireless communication networks. Users use the devices to download files, music, e-mail messages, and other data, as well as to watch streaming video, play streaming music, play games, surf the web, and engage in other data intensive activities.
Packet data latency is one of the performance metrics widely used to benchmark system performance. Packet data latency is important not only for the perceived responsiveness of the system; it is also a parameter that indirectly influences the throughput. Certain traffic types are latency sensitive and require reduced latency for their data packets. Such latency sensitive traffic types can include Voice over Internet Protocol, such as for telephone calls, can include gaming, can include automobile control signals, and can include other time sensitive traffic types. HTTP/TCP is the dominating application and transport layer protocol suite used on the internet today with the TCP slow start period is a significant part of the total transport period of the packet stream. During TCP slow start the performance is latency limited. Hence, improved latency can improve the average throughput, for this type of TCP-based data transactions. The latency sensitive traffic types require downlink and uplink packet latency reduction, such as reduction in the time taken for a device in connected mode to transmit and receive data and signals. This is opposed to normal latency packets that are used for traffic types like file downloading and uploading, which are less latency sensitive because the latency minimally affects the file transfers and the normal latency is not readily apparent to a user.
In order to support the latency sensitive traffic types and other latency sensitive new use cases, to expand the application of LTE and other wireless communication systems to a wider set of scenarios, and to enhance LTE with better user perceived experiences there is a need to support lower latency through enhancement of LTE and other wireless communication systems. Unfortunately, present devices do not adequately provide a structure for low latency transmissions. Thus, there is a need for a method and apparatus for low latency transmissions.